Installed and used as a dummy power supply (standard power supply) at the tip side of a certain rotating equipment. Connect resistors in parallel at the root side, connect oscilloscope probes, use forced trigger to log whether there is no problem with rotary contacts. Previously I was using 3.7V lithium rechargeable battery (18650), but since there was no switch in the battery box, I introduced it here as a test. If there is no problem, I will replace them sequentially. The red-black lead pretends to be pretty shy.